Why buy a brand new costume for your kid when you can "Green Your Halloween"? That's the idea behind MB Green Halloween, a new Facebook group dedicated to helping parents of Manhattan Beach school kids find and share previously worn Halloween costumes.

The concept is simple, and will be familiar to those who use the local "Buy Nothing" group on Facebook: Share a picture of a Halloween costume that you're ready to give away, or name a costume that you're looking for. Then other members can chime in if they're either interested in your costume, or if they have a costume to give you.

The group was created by two Manhattan Beach parents, Michelle Porter and Paula Davis. Both are environmental leaders within the school district: Porter is vice chair of MBUSD's Green Committee, and Davis is co-chair for the Green Team at Robinson.

The MB Green Halloween page was created as a way to promote re-use, conserve resources and help the environment, and is part of the district's ongoing environmental efforts, said Porter. (MBUSD has been honored by the U.S. Department of Education as a National Green Ribbon District.)

"One of our goals is to help make environmentally friendly choices fun and easy for everyone," said Porter. "We were brainstorming, and this is an idea we all got on board with pretty quickly."

"I think it’s so effective - it helps both parties, and it’s such a good way to reuse things and repurpose them," added Davis.

The group now has more than 110 members and has been growing rapidly as the word is spread around the district.

(Note: The group is currently open only to MBUSD families because it is part of the school district's green efforts. You will be asked which school your child is in when you request to join the group.)

Porter and Davis said they were inspired by recent estimates of the waste created by the buy-more culture, especially as it relates to clothing. The consignment resale site ThredUp estimates that if everyone bought one used item instead of new this year, it would save the equivalent of two billion pounds of CO2 emissions (equivalent to taking 76 million cars off the road for a day), 23 billion gallons of water, and four billion kilowatt hours of energy.

Furthermore, Halloween is an extremely wasteful holiday in environmental terms. Many costumes are made from polyester, which is difficult to recycle. According to Recycling Product News, throwaway Halloween costumes contribute to over 12 million pounds of textile waste generated each year in the U.S., and nearly 85 percent of costumes winding up in landfills.

And among those families who haven't thrown away Halloween costumes, many have only-worn-once costumes taking up space in closets and storage areas - making it even more of a good reason to pass those costumes along.

Davis said that when she went through her closets, "I found the whole range of kids' costumes - all the way back to when they were babies."

Davis and Porter added that the group was also open to sharing adult-sized costumes, either for taller middle and high school kids, or even for parents - who are often called upon to wear costumes for school events or trick-or-treating.